Mechanical absorption systems for an active bonnet hinge

ABSTRACT

The invention relates to a safety device for raising the bonnet of a motor vehicle in the event of a collision with a pedestrian. The safety device includes a pyrotechnic actuator provided with a thrust piston secured to a mechanism for raising the bonnet and able to deploy the said mechanism which is itself secured to the said bonnet, and a blocking device intended to block the said actuator in a given position. The main characteristic of this device is that it is made up of a shock-absorbing device employed when a pedestrian hits the bonnet which has been raised, so that the assembly consisting of the bonnet, the raising mechanism and the piston can move under the effect of the impact while at the same time being retarded.

This is a Division of application Ser. No. 11/254,716 filed Oct. 21,2008, which claims the benefit of French Patent Application No. 0412343filed Nov. 22, 2004. The disclosure of the prior applications is herebyincorporated by reference herein in its entirety.

BACKGROUND

The technical field of the invention is that of the devices used in thefield of automotive safety to protect a pedestrian in the event of afrontal impact between the said pedestrian and a motor vehicle.

When a pedestrian is struck by the front end of a motor vehicle, thepedestrian's head often comes into direct contact with the bonnet of thevehicle. The impact of the head on the bonnet causes the bonnet todeform. This deformation often occurs to such a point that the bonnetcomes into contact with the engine block and any rigid parts such assuspension leg turrets, windscreen wiper mechanisms, etc. The movementof the pedestrian's head is then abruptly halted by the bonnet cominginto contact with the engine block and therefore experiences a violentdeceleration which may cause the pedestrian serious injury.

The prior art already knows devices which, in the event of an impactbetween a pedestrian and a motor vehicle, allow the vehicle bonnet to beraised by a certain amount so as to prevent the pedestrian's limbs andespecially his head from being stopped, in the impact against thebonnet, by the engine block situated just under the bonnet. In thedevices of the prior art, the raising of the bonnet is performed at therear end of the bonnet, that is to say at the windscreen end, which isthe opposite end to the end used for opening or closing the bonnet innormal operation, the bonnet remaining fixed at the front end of themotor vehicle.

Patent FR 2 848 947 relates to a safety device for raising the bonnet ofa motor vehicle in the event of a collision, this device being situatedunder the said bonnet and comprising a mechanism for raising the saidbonnet and an actuator, the said bonnet comprising a structure which, innormal operation, allows it to be opened or closed about an axis knownas the pivot axis.

The main characteristic of this device is that the raising mechanismfirst of all undergoes an unlocking phase by performing a first,translational, movement.

The main characteristic of this device is that it undergoes an unlockingphase through a translational movement, followed by a deployment phasein a rotational movement. The safety device also foresees a later,shock-absorbing, phase allowing the bonnet to move with the struckpedestrian so as to lessen the effect of the said impact. However, noway of embodying such a shock-absorbing device is described. The safetydevices according to the invention exhibit shock-absorbing devices thequalities of which are tailored to the requirements associated with thetight confines of motor vehicles and their low cost, namely, small size,simplicity of design and great reliability. Simplicity of design meansthat the shock-absorbing devices have not to require the addition ofparts that need complex and costly machining.

SUMMARY

The subject of the present invention is a safety device for raising thebonnet of a motor vehicle in the event of a collision with a pedestrian,comprising a pyrotechnic actuator provided with a thrust piston securedto a mechanism for raising the bonnet and able to deploy the saidmechanism which is itself secured to the said bonnet, and a blockingdevice intended to block the said actuator in a given position,characterized in that it comprises a shock-absorbing device employedwhen a pedestrian hits the bonnet which has been raised, so that theassembly consisting of the bonnet, the raising mechanism and the pistoncan move under the effect of the impact while at the same time beingretarded. More specifically, since the raising mechanism is blocked in agiven position corresponding to a certain raising of the bonnet, theassembly consisting of the bonnet, the said mechanism and the piston canbe likened to a single rigid component. The shock-absorbing device hasto allow the said assembly to move under the effect of a pedestrianimpact, in the opposite direction to the direction in which the bonnetis raised, so as to allow the bonnet to move with the said pedestrian inorder to absorb the shock of the impact. For an understanding of theinvention and, in particular, of claim 1, the raising mechanismcomprises a link rod and a raising lug.

Advantageously, the pyrotechnic actuator possesses a hollow cylindricalbody containing the piston.

According to a first preferred embodiment of the invention, theshock-absorbing device is located inside the pyrotechnic actuator. Thisembodiment encourages the shock-absorbing device to be of minimum bulk.

As a preference, the shock-absorbing device consists structurally of theblocking device. In other words, the safety devices according to theinvention have just one mechanical device which, depending on theapplied stresses, may either block the raising mechanism or absorb theshock of the “bonnet+raising mechanism+piston” assembly.

Advantageously, the hollow body exhibits a small-diameter upstream partand a larger-diameter downstream part which parts are connected to oneanother by a divergent passage, and the piston comprises a peripheralgroove partially delimited by the internal wall of the said upstreampart. Thus, the piston is positioned in the hollow body in such a waythat the groove lies in the upstream part of the said body, the saidpiston being able to slide in the said upstream part.

As a preference, the groove has a U-shaped cross section so that itexhibits two side walls facing one another and parallel to each other.

Advantageously, a prestressed member is housed in the groove, bearingagainst the internal wall of the upstream part.

In this way, withdrawal from the internal wall of the upstream partcould cause the said member to relax.

As a preference, the prestressed member consists of a snap ring which isan annular component having the shape of a ring provided with anopening. Thus, a radial pressure uniformly distributed over the saidcomponent allows the latter to deform elastically in such a way as tomove the two ends that delimit the said opening closer together.

According to an alternative form of the embodiment of the invention, thesnap ring has a circular cross section.

Advantageously, initiation of the actuator causes the piston to slideuntil the groove reaches the downstream part of the body, thus causingthe snap ring to relax.

In the absence of any particular stress, the snap ring, which isrelaxed, prevents the piston from moving in the opposite direction.

As a preference, the material of the upstream part of the body isdeformable so as to allow the piston, following a pedestrian impact, tomove in the opposite direction, carrying with it the snap ring whichforcibly enters the said upstream part of the body which deforms. Thelength traveled by the snap ring in the upstream part corresponds to theshock-absorbing distance.

According to another preferred embodiment of the invention, theshock-absorbing device consists of at least one weakening featuresituated on the hollow body of the actuator. Advantageously, the saidfeature contributes towards reducing the total length of the said bodyin the event of a pedestrian impact.

In other words, since the piston, which is secured to the raisingmechanism and to the bonnet, is blocked, the hollow cylindrical bodywill tend to crumple on itself in the direction of its axis in the eventof a pedestrian impact.

The reduction in the length of the hollow body corresponds to theshock-absorbing distance.

Advantageously, the blocking device is produced by means of a compressedsnap ring situated in a peripheral groove of the piston and whichrelaxes when the said groove opens into a widened zone of the hollowbody thus preventing the piston from moving in the opposite direction.As a preference, the said zones are separated from one another by aninternal shoulder. Preferably, the snap ring has a rectangular crosssection.

Thus, the relaxed snap ring is blocked against the internal shoulder ofthe body, preventing the piston from moving in the opposite direction.

According to a second preferred embodiment of the invention, theshock-absorbing device is external to the actuator. Advantageously, theactuator is mounted on a support piece secured to the vehicle and theshock-absorbing device is secured to the said piece.

As a preference, the actuator is in contact with the support piece via aprotrusion secured to the said actuator, the said protrusion being ableto pivot in the said piece.

Advantageously, the protrusion is of cylindrical shape.

Preferably, the shock-absorbing device consists of a deformable pieceborne by the support piece and situated in contact with the pyrotechnicactuator. Preferably, the protrusion is placed in a notch of the supportpiece, the said protrusion being in contact with the deformable piece.

According to a second preferred embodiment of the invention, thedeformable piece has at least one weakening feature able to encouragethe said piece to deform following a pedestrian impact.

It is necessary for the hollow body of the actuator to be in contactwith the deformable piece because since the piston remains blocked inthe said body following a pedestrian impact, it is the said body whichwill transmit the impact to the said deformable piece.

According to another preferred embodiment of the invention, thedeformable piece consists of a corrugated sheet, able to crumple onitself following a pedestrian impact transmitted by the body of theactuator to the said sheet.

Preferably, the support piece has means for guiding the said protrusion,and the shock-absorbing device is included in the said guide means.

Advantageously, the guide means are represented by two oblong openingsthrough each of which the protrusion passes, the said protrusion beingable to move in the said openings following a pedestrian impact with thebonnet. As a preference, the openings have, on their outline, aplurality of deformable teeth. The teeth thus increase the roughness ofthe outline of the said openings. Following the pedestrian impact, thebody of the actuator moves, driving the protrusion in the directiondictated by the oblong openings. The movement of the said protrusion inthe said openings causes the teeth to bend, thus retarding the saidmovement.

According to another preferred embodiment of the invention, the width ofthe openings is smaller than the width of the said protrusion. In thisway, under the effect of the impact of a pedestrian with the bonnet, theprotrusion is moved forcibly along the said openings, widening them.

The safety devices according to the invention have the advantage ofhaving a well-controlled shock-absorbing function thanks to mechanicaldevices that are simple, perfectly suited to the small volumesavailable, conceded by motor vehicles. In addition, this shock-absorbingfunction can be tailored to a given configuration through a simplestructural modification of the materials involved or simply by changingthe material since the said materials are in commonplace use and haveperfectly known mechanical properties.

A detailed description of four preferred embodiments of a safety deviceaccording to the invention is given hereinafter with reference to FIGS.1 to 19.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view in longitudinal section of a safety device according tothe invention equipped with a shock-absorbing device involving a snapring and which has not yet functioned.

FIG. 2 depicts the device of FIG. 1 once the shock-absorbing device hasfunctioned.

FIG. 3 is an enlarged view in longitudinal axial section of ashock-absorbing device involving a snap ring.

FIG. 4 is an enlarged view in longitudinal axial section of the deviceof FIG. 3, following a pedestrian impact with the bonnet.

FIG. 5 is a view in partial longitudinal section of a safety deviceaccording to the invention, having an actuator with a weakening feature.

FIG. 6 depicts the device of FIG. 5, following a pedestrian impact withthe bonnet.

FIG. 7 is an enlarged view in longitudinal axial section of apyrotechnic actuator of a safety device according to the invention,having a first variant of the weakening feature.

FIG. 8 depicts the actuator of FIG. 7 following the pedestrian impactwith the bonnet.

FIG. 9 is an enlarged view in longitudinal axial section of apyrotechnic actuator of a safety device according to the invention,having a second variant of the weakening feature.

FIG. 10 depicts the actuator of FIG. 9 following the pedestrian impactwith the bonnet.

FIG. 11 is a side view of a safety device according to the inventionequipped with an external shock-absorbing device comprising a piece witha weakening feature.

FIG. 12 depicts the device of FIG. 11 following a pedestrian impact withthe bonnet.

FIG. 13 is a perspective view of the relative arrangement of thedeformable piece and of the pyrotechnic actuator.

FIG. 14 is a perspective view of a concertina piece acting as ashock-absorbing device for a safety device according to the invention.

FIG. 15 depicts the piece of FIG. 14 following a pedestrian impact withthe bonnet.

FIG. 16 is a side view of part of the support piece for the pyrotechnicactuator, the said piece being equipped with two toothed side openings.

FIG. 17 depicts the part of the support piece of FIG. 16 following apedestrian impact with the bonnet.

FIG. 18 is a side view of part of the support piece for the pyrotechnicactuator and the said piece being equipped with two narrow sideopenings.

FIG. 19 depicts the part of the support piece of FIG. 18 following apedestrian impact with the bonnet.

DETAILED DESCRIPTION

With reference to FIGS. 1 and 2, a first preferred embodiment of asafety device 1 according to the invention comprises a pyrotechnicactuator 2, a link rod 3, a raising lug 4 and a locking hook 5. The linkrod 3 has the shape of an elongate part with a variable U-shaped crosssection so that it has two mutually parallel faces. The said link rod 3has an upstream part 6 able to pivot about a pivot pin 7 passing throughits two parallel faces, and a downstream part 8 able to be raised whenthe upstream part 6 pivots about its pin 7.

The said downstream part 8 comprises, on each of these faces, anelongate opening 9, each opening having, passing through it, a pivot pin10 secured to the raising lug 4, the said lug 4 itself being secured tothe bonnet 11. The link rod 3 has, on one of its faces, a fixedprotrusion 12 equipped with a flat 13. The pyrotechnic actuator 2comprises a cranked rear part 14 in which a pyrotechnic charge 15 ishoused and a front part in the form of a straight hollow cylindricalbody 16 in which a piston 17 is housed. The said straight hollow body 16has a small-diameter upstream part 18 and a larger-diameter downstreampart 19 which parts are connected to one another by a divergent passage20, the said upstream part 18 being in contact with the cranked rearpart 14. The piston 17 is made up of a widened body 21 extended by acylindrical rod 22 comprising a shoulder 25. In this way, the rod 22exhibits a widened part in contact with the widened body 21 of thepiston 17 and a smaller-diameter part. The said widened body 21 of thepiston 17 has a peripheral groove 23 and exhibits an outside diameterslightly smaller than the inside diameter of the upstream part 18 of thehollow cylindrical body 16 of the actuator 2. The piston 17 is placed inthe actuator 2 in such a way that its widened body 21 is housed in theupstream part 18 of the straight hollow body 16 and can slide thereinhermetically. Thus, the peripheral groove 23 is partially delimited bythe internal wall of the said upstream part 18 of the hollow body 16.The actuator 2 is able to pivot at the same time as the link rod 3 abouta pivot pin not depicted in the figures and which is parallel to thepivot pin 7 of the said link rod 3. With reference to FIGS. 3 and 4, thegroove 23 has a shoulder 26 to distinguish a smaller-diameter part 27corresponding to the deepest part of the said groove 23 from alarger-diameter part 28. A prestressed snap ring 24, of circular crosssection, bearing against the internal wall of the upstream part 18 ofthe hollow cylindrical body 16 is housed in the said groove 23 at itsdeepest part. An electro-pyrotechnic initiation system is positionednear the pyrotechnic charge 15 to initiate its combustion. The hook 5 ismounted to pivot on the vehicle and can effect a rotary movement about apivot pin 29.

The way in which this first preferred embodiment of the safety device 1according to the invention works is as follows.

An electrical impulse device sets off the electro-pyrotechnic ignitionsystem which initiates the combustion of the pyrotechnic charge 15.

The gases delivered move the piston 17 which, in a first phase, unlocksthe safety device 1 by exerting thrust on the hook 5 and which, in asecond phase, comes to bear against the flat 13 of the protrusion 12 ofthe link rod 3 via the shoulder 25 of its rod 22, so as to cause thesaid link rod 3 to rotate about its pin 7. The rotation of the said linkrod 3 leads to the raising of the bonnet 11 by virtue of the raising lug4, the pivot pin 10 of which can move in the elongate openings 9 of thedownstream part 8 of the link rod 3. Thus, the piston 17 slides in thestraight hollow cylindrical body 16 until the peripheral groove 23reaches the divergent passage 20 and the snap ring 24 relaxes to occupythe shallower part 28 of the said groove 23. In this final positionwhich corresponds to the one depicted in FIGS. 1 and 3, the snap ring 24prevents any movement of the piston 17 in the opposite direction, unlessexternal stress is exerted. Thus, the assembly represented by the bonnet11, the raising lug 4, the link rod 3 and the piston 17 constitutes arigid component. All of this first phase corresponds to a phase ofarming the safety device 1.

With reference to FIG. 4, in the event of a pedestrian impact with thebonnet 11 in the direction shown by the arrow in FIG. 1, the impact thusgenerated is transmitted to the piston 17, and its intensity is suchthat the said piston 17 will begin to move in the opposite direction,carrying with it the snap ring 24 which is relaxed. During this movementin the opposite direction, the said snap ring 24 forcibly enters thesmall-diameter upstream part 18 of the hollow cylindrical body 16 whichdeforms. This phase of deforming the hollow cylindrical body 16corresponds to a phase of absorbing the shock of the bonnet 11 becausethe said bonnet 11 can move under the effect of the pedestrian impactwhile at the same time being retarded. With reference to FIG. 4, themovement of the bonnet 11 halts when the safety device 1 returns to there-engagement position. In this embodiment the snap ring 24 has had thedual function of acting as a blocking device and of acting as ashock-absorbing device.

With reference to FIGS. 5 and 6, a second preferred embodiment of asafety device 101 according to the invention comprises a pyrotechnicactuator 102, a link rod 103, a raising lug 104 and a locking hook 105.The link rod 103 has the shape of an elongate piece of variable.U-shaped cross section so that it exhibits two mutually parallel faces.The said link rod 103 has an upstream part 106 able to pivot about apivot pin 107 passing through its two parallel faces and a downstreampart 108 able to be raised when the upstream part pivots about its pin107.

The said downstream part 108 comprises, on each of its faces, anelongate opening 109, each one having, passing through it, a pivot pin110 secured to the raising lug 104, the said lug 104 itself beingsecured to the bonnet 111.

On one of its faces, the link rod 103 has a fixed protrusion 112equipped with a flat 113. The pyrotechnic actuator 102 comprises acranked rear part 114 in which a pyrotechnic charge 115 is housed and afront part in the form of a straight hollow cylindrical body 116 inwhich a piston 117 is housed.

The piston 117 is made up of a widened body 121 extended by acylindrical rod 122 comprising a shoulder 125. In this way, the rod 122has a widened part 130 in contact with the widened body 121 of thepiston 117 and a smaller-diameter part 121, the said widened part 130having a peripheral groove 123. The straight hollow cylindrical body 116has one end in contact with the cranked rear part 114 and a free endequipped with an opening to allow the widened part 130 of the rod 122 topass, the said opening having a diameter greater than that of the saidwidened part 130. A cylindrical piece 132 provided with a passage, thediameter of which is appreciably greater than the diameter of the saidwidened part 130 of the rod 122 but smaller than the diameter of theopening, is fixed inside the straight hollow cylindrical body 116, nearits free end. Thus, the widened part 130 of the rod 122 can slidehermetically in the said piece 132 because the opening of the hollowcylindrical body 116, which is too wide, does not permit it. The piston117 is placed in the actuator 102 in such a way that the peripheralgroove 123 is partially delimited by the internal wall of the hollowcylindrical piece 132. A prestressed snap ring 124, of rectangular crosssection, is housed in the said groove 123, bearing against the saidinternal wall. The actuator 102 is able to pivot at the same time as thelink rod 103 about a pivot pin not depicted in the figures and which isparallel to the pivot pin 107 of the said link rod 103. With referenceto FIGS. 7 and 9, the straight hollow cylindrical body 116 has aweakening feature 133, 134 either in the form of a narrow bulging 133 ofthe said body 116 or in the form of two successive restrictions 134 ofthe said body 116.

The way in which this second preferred embodiment of a safety device 101according to the invention works is as follows.

An electrical impulse sets off the electropyrotechnic ignition systemwhich initiates the combustion of the pyrotechnic charge 115. The gasesdelivered move the piston 117 which, in a first phase, unlock the safetydevice 101 by exerting thrust on the hook 105 and which, in the secondphase, comes to bear against the flat 113 of the protrusion 112 of thelink rod 103 via the shoulder 125 of its rod 122 to cause the said linkrod 103 to rotate about its pin 107. The rotation of the said link rod103 leads to the raising of the bonnet 111 by virtue of the raising lug104, the pivot pin 110 of which can move in the elongate openings 109 ofthe downstream part 108 of the link rod 103. Thus, with reference to theFIGS. 7 and 9, the piston 117 slides in the straight hollow cylindricalbody 116 until the peripheral groove 113 reaches the opening at the endof the straight hollow cylindrical body 116 and the snap ring 124relaxes. In this position, the relaxed snap ring 124 acts as a blockingdevice, preventing, inter alia, any movement of the piston 117 in theopposite direction. In this way, the assembly represented by the bonnet111, the raising lug 104, the link rod 103 and the piston 117constitutes a rigid component. All of this first phase corresponds to aphase of arming the safety device 101 which is identical to the phasedescribed in respect of the first preferred embodiment of the invention.

Upon pedestrian impact with the bonnet 111 in the direction shown by thearrow in FIG. 5, the impact thus generated is transmitted to the piston117, solidly blocked by the snap ring 124. With reference to FIGS. 8 and10, the forces will then be transferred to the weakening features 133,134 of the hollow cylindrical body 116 which will react by crumpling onitself, thus leading to a reduction in its length. This crumpling allowsthe bonnet 111 to move under the effect of the pedestrian impact, whileat the same time being retarded.

With reference to FIG. 6, the movement of the bonnet 111 halts when thesafety device 1 returns to the re-5 engaged position.

With reference to FIGS. 11 and 12, a third preferred embodiment of asafety device 201 according to the invention differs from the secondpreferred embodiment described hereinabove in that the weakeningfeatures are no longer produced on the body of the pyrotechnic actuator202 but are produced on a deformable piece 240 placed in contact withthe said actuator 202, on the same side as the pyrotechnic charge, notdepicted in FIGS. 11 and 12. The safety device 201 is fixed to thevehicle by means of an elongate support piece 241 having a variableU-shaped cross section, the said piece 241 having, on each of these twoparallel edges, an elongate notch 242 each facing the other. The crankedrear part of the pyrotechnic actuator 202 comprises a cylindricallateral protrusion 243, the diameter of which is appreciably smallerthan the width of the notch 242, and the actuator 202 is positioned withrespect to the support piece 241 in such a way that the said protrusion243 lies in the closed end of the said notch 242. During the phase ofarming the safety device 201, the protrusion 243, the axis of which isparallel to the pin 207 of the link rod 203, will constitute the axis ofrotation of the actuator 202.

With reference to FIG. 13, the deformable piece 240 is fixed to thesupport piece 241 by means of a peg 244 secured to the deformable piece240 and which becomes inserted in a notch of the said support piece 241.The deformable piece 240 comprises a body 246 which on the whole has aU-shaped cross section and is extended by two parallel lugs 245 eachhaving, at its end, a notch intended to house the protrusion 243.

The support piece 241, the deformable piece 240 and the pyrotechnicactuator 202 are arranged in such a way that the protrusion 243 findsitself blocked in the closed end of the elongate notch 242 of thesupport piece 241 by the notches of the two lugs 245 of the deformablepiece 240. The body 246 of the deformable piece 240 comprises aweakening feature 247 in the form of a narrow restriction.

The way in which this third preferred embodiment of a safety device 201according to the invention works is as follows.

The phase of arming the safety device 201 is in every respect identicalto the equivalent phase described for the first and second preferredembodiments of the invention.

Upon pedestrian impact with the bonnet 211 in the direction shown by thearrow in FIG. 11, since the piston 217 is solidly blocked in theactuator 202 by the blocking device involving the snap ring ofrectangular cross section, the impact is transmitted to the protrusion243 having passed through the raising lug 204 and the link rod 203. Theintensity of the said impact is such that the actuator 202 will exertthrust on the deformable piece 240 via the protrusion 243, the saidpiece 240 then crumpling on itself at its weakening feature 247. Thisdeformation of the piece 240 allows the bonnet 111 to move under theeffect of the pedestrian impact, while at the same time being retarded.According to FIG. 12, the movement of the bonnet 211 halts when thesafety device 201 has returned to the re-engaged position. It should benoted that, during the arming phase, the piece 240 is sized in such away as to counter the thrust forces of the actuator 202 withoutexperiencing plastic deformation.

With reference to FIG. 14, the deformable piece may consist of acorrugated sheet 250 placed in contact with the pyrotechnic actuator.With reference to FIG. 15, in the event of a pedestrian impact, the saidactuator exerts thrust in the direction shown by the arrow on the saidsheet which will crumple, allowing the bonnet to move while at the sametime being retarded.

With reference to FIGS. 16 and 17, a fourth preferred embodiment of asafety device according to the invention differs from the thirdpreferred embodiment described above in that the deformable piece hasbeen removed and in that the protrusion 343 passes through two oblongopenings 344 facing one another and placed on the two parallel edges ofa support piece 345 secured to the vehicle and having a variableU-shaped cross section. The axis of the protrusion 343 is parallel tothe pivot pin 307 of the link rod. Each of the two openings 344comprises a plurality of triangular and deformable teeth 346, situatedalong their outline.

The way in which this fourth preferred embodiment of a 25 safety deviceaccording to the invention works is as follows.

The phase of arming the safety device is in every respect identical tothe equivalent phase described for the first three embodiments of theinvention described hereinabove.

Upon pedestrian impact with the bonnet, the impact is transmitted to theprotrusion 343. The intensity of the said impact is such that theactuator 302 will move in the direction shown by the arrow in FIG. 13,carrying along the protrusion 343 which itself moves in the openings 344crumpling the teeth 346 as it passes. The openings 344 encourage themovement of the bonnet following a pedestrian impact with the bonnet,and the teeth 346, which crumple, retard the said movement.

With reference to FIGS. 18 and 19, the two oblong 5 openings 354 aresmaller in width than the diameter of the protrusion 353.

Following the pedestrian impact with the bonnet, the actuator 302 movesin the direction shown by the arrow in FIG. 18 carrying along theprotrusion 353 which itself moves forcibly in the openings 354. Theopenings, which widen as they deform as the said protrusion 353 passes,contribute to retarding the movement of the bonnet.

1. A safety device for raising a bonnet of a motor vehicle in the eventof a collision with a pedestrian, comprising: a pyrotechnic actuatorpossessing a hollow body containing a thrust piston secured to amechanism for raising the bonnet and able to deploy said mechanism whichis itself secured to said bonnet, a blocking device that blocks saidactuator in a given position, and a shock-absorbing device employed whena pedestrian hits the bonnet which has been raised, so that the assemblyconsisting of the bonnet, the raising mechanism and the piston can moveunder the effect of the impact while at the same time being retarded,wherein said shock-absorbing device is secured to a support piecesecured to the vehicle and in that the actuator is in contact with saidsupport piece via a protrusion secured to said actuator, said protrusionbeing able to pivot in said piece.
 2. The device according to claim 1,wherein said protrusion is of a cylindrical shape.
 3. The deviceaccording to claim 1, wherein said shock-absorbing device consists of adeformable piece borne by said support piece and situated in contactwith the actuator.
 4. The device according to claim 3, wherein theprotrusion is placed in a notch of said support piece, said protrusionbeing in contact with said deformable piece.
 5. The device according toclaim 4, wherein said deformable piece has at least one weakeningfeature able to encourage its deformation.
 6. The device according toclaim 3, wherein said deformable piece consists of a corrugated sheet.7. The device according to claim 1, wherein said support piece has meansfor guiding said protrusion and said shock-absorbing device is includedin said guide means.
 8. The device according to claim 7, wherein saidguide means comprises two oblong openings through each of which theprotrusion passes, said protrusion being able to move in said openingsfollowing a pedestrian impact with the bonnet.
 9. Device according toclaim 8, wherein said openings have a plurality of deformable teeth onan outline of said openings.
 10. Device according to claim 8, whereinsaid openings have a width smaller than the width of said protrusion.